Article continues below advertisementKendall Jenner is keeping up with her car collection.The Kardashians star, 29, bared her backside and six-pack stomach in a gray Porsche on Thursday, July 31. Article continues below advertisementSource: @kendalljenner/InstagramKendall Jenner stunned in a skimpy sports bra and shorts.Jenner rocked a cleavage-baring black sports bra and biker shorts from Alo. She appeared to be on her way to a workout, with athletic sneakers and her hair clipped into a messy bun.